不同耕作方式下秸秆还田对土壤活性有机碳的影响

Effect of straw returning on soil labile organic carbon under different tillage measures

针对黄土高原雨养农业区干旱逆境下农田土壤有机碳累积、矿化的平衡点低等问题,探索了不同耕作方式下秸秆还田对土壤有机碳的影响.采用埋袋法研究了传统耕作不还田（T）、传统耕作秸秆还田（TS）、免耕秸秆覆盖（NTS）、传统耕作秸秆还田加薄膜覆盖（TPS）4种耕作方式对土壤有机碳和活性碳组分含量的影响及其动态变化特征.结果表明：秸秆还田能显著增加土壤有机碳和活性有机碳含量;不同耕作方式下土壤有机碳和活性有机碳含量存在差异,其中土壤有机碳（SOC）含量为TPS〉NTS〉TS〉T,水溶性有机碳含量（WSOC）为TS〉TPS〉NTS〉T,易氧化有机碳（ROOC）含量为NTS〉TS〉TPS〉T;秸秆还田一年内SOC、WSOC、ROOC含量整体呈减小趋势;90-180d土壤有机碳在NTS减少幅度最大,达到9.18%,土壤水溶性有机碳TS减少最大;易氧化有机碳在180-270d减少较多,其含量顺序为NTS〉TS〉TPS〉T.

In connection with the problems of farmland soil organic carbon accumulation and low organic carbon mineralization balance under drought stress in Loess Plateau rainfed agriculture area.In this paper,using buried bag method explored the response discipline of soil organic carbon of return field straw under different tillage in this area.The dynamic characteristics of soil organic carbon and activated carbon component contents under four different tillage measures （conversational tillage,conversational tillage with straw incorporated,no-till with straw cover,conversational tillage with straw incorporated of plastic film mulching）were studied.The results showed that,straw returning could improve the content level of soil total organic carbon and labile organic carbon.The content of soil organic carbon and labile organic carbon were different in different tillage methods,soil organic carbon （SOC）content was in the order of TPS〉NTS〉TS〉T;water soluble organic carbon content was in the order of TS〉TPS〉NTS〉T;readily oxidized organic carbon （ROOC）content was in the order of NTS〉TS〉TPS〉T;the readily oxidized organic carbon content was in the order of NTS〉TS〉TPS〉T.The SOC,WSOC and ROOC content appeared a overall decreasing trend under the one year returning straw condition,soil organic carbon of the NTS treatment decreased 9.18% which was the sharpest,soil water-soluble organic carbon reduced maximum in the 90 d-180 d,readily oxidized organic carbon reduced comparatively large in the 180 d-270 d and was in the order of NTS〉TS〉TPS〉T.